So, in a tube amp, what's a transformer do?
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That90'sGuy
DyzaBoyzologist
Re: So, in a tube amp, what's a transformer do?
I'm not sure about this, but I was under the impression transformers are what generate the electricity in the amp current.
I'm not sure about this, but I was under the impression transformers are what generate the electricity in the amp current.
Duke of Metal
New member
Re: So, in a tube amp, what's a transformer do?
I believe the output transformers (the one your asking about) are basicly what pushes the signal through to the speakers and they are what provides the wattage of an amp.
Feel free to correct me if I am mistaken people.
Duke
I believe the output transformers (the one your asking about) are basicly what pushes the signal through to the speakers and they are what provides the wattage of an amp.
Feel free to correct me if I am mistaken people.
Duke
Jeff Seal
New member
Re: So, in a tube amp, what's a transformer do?
Well...here goes.....and believe it or not this is a "simplified" expalnation!
Transformers, regardless of what they're in simply allow an Alternating Current source to be passed from one side of the transformer (primary side) to another (secondary side or sides) and in the process can increase or decrease or simply match what goes into it. This is achieved by simply wrapping a wire around any thing will conduct electricity with wire that is coated or "insulated" so that the wire won't actually touch the core, but creates a magnetic field in the core. This field is passed on to any other wire that's wrapped around the same core. How many times the primary wire is wrapped around the core determines the primary/secondary relationship.
If the primary winding is wrapped around the core 1,000 times, and another wire is wrapped around the same core 1,000 times then the transformer puts out exactly what goes into it....we'll use 120v for an example.
If 120v AC is applied to the primary side with 1,000 windings (or "turns"), the secondary side, also with 1,000 windings, will produce 120v AC...not real useful except in specific applications!
However, If the secondary windings are doubled (2,000) windings around the core....the output of the transformer will be twice or 240v, while the primary side remains at 120v... Conversely, if the secondary windings are cut in half (500) windings, the output will be only 60v, again with the primary still running at 120v....
A convienent practical application.... the 9v power supply for most stompboxes.....uses a transformer with 1000 windings on the primary(120v) but only about 80 windings to result in 9v required for your average Tube Screamer or similar unit......however the 9v Ac is also converted to DC by a rectifier that comes after the transformer...we'll leave that for another discussion...... hopefully so far, this hasn't confused more than helped.
Tube amps require plate voltages around 480v or so to operate, so the Power Transformer takes the 120v source and converts it to 480v....in the above example 1,000 turns on the primary side and 4,000 turns on the secondary side = 480v.... but they also require a measley 6.3 volts to run the heaters, so another set of windings is wrapped around the core, independent of the others only about 50 times.... yet another set of windings produces the 60v needed for the bias supply.....500 turns on this winding!
O.K. so that covers the Power Transformer function.....in order to understand how the Output Transformer works, you have to understand that Ac voltages aren't always just 120v....tubes generate about what the plate voltage is (around 480v) AC output max which is way more than any speaker can handle, so another transformer steps this votage down to a managable level the speaker can use it.
Another thing about transformers is what they don't do, they don't pass DC (direct current) only AC since there is no physical connection between the windings. The primary side of the Output transformer has the full 480v running through it and the tubes modulate that voltage..(we'll leave it at that for now)
Because the amount of windings vary greatly to fit the application, other issues such as wire gauge come into play, and generally speaking the larger the transformer, the better quality....or the better power capability (has nothing to do with how the amp is voiced, just usually means it can handle more!) The size of the field created, the wire gauge and number of windings all determine how transformers pass electricity and bigger is not always better, just different.......
...well, this went way long, but hope it helped
Jeff Seal
Well...here goes.....and believe it or not this is a "simplified" expalnation!
Transformers, regardless of what they're in simply allow an Alternating Current source to be passed from one side of the transformer (primary side) to another (secondary side or sides) and in the process can increase or decrease or simply match what goes into it. This is achieved by simply wrapping a wire around any thing will conduct electricity with wire that is coated or "insulated" so that the wire won't actually touch the core, but creates a magnetic field in the core. This field is passed on to any other wire that's wrapped around the same core. How many times the primary wire is wrapped around the core determines the primary/secondary relationship.
If the primary winding is wrapped around the core 1,000 times, and another wire is wrapped around the same core 1,000 times then the transformer puts out exactly what goes into it....we'll use 120v for an example.
If 120v AC is applied to the primary side with 1,000 windings (or "turns"), the secondary side, also with 1,000 windings, will produce 120v AC...not real useful except in specific applications!
However, If the secondary windings are doubled (2,000) windings around the core....the output of the transformer will be twice or 240v, while the primary side remains at 120v... Conversely, if the secondary windings are cut in half (500) windings, the output will be only 60v, again with the primary still running at 120v....
A convienent practical application.... the 9v power supply for most stompboxes.....uses a transformer with 1000 windings on the primary(120v) but only about 80 windings to result in 9v required for your average Tube Screamer or similar unit......however the 9v Ac is also converted to DC by a rectifier that comes after the transformer...we'll leave that for another discussion...... hopefully so far, this hasn't confused more than helped.
Tube amps require plate voltages around 480v or so to operate, so the Power Transformer takes the 120v source and converts it to 480v....in the above example 1,000 turns on the primary side and 4,000 turns on the secondary side = 480v.... but they also require a measley 6.3 volts to run the heaters, so another set of windings is wrapped around the core, independent of the others only about 50 times.... yet another set of windings produces the 60v needed for the bias supply.....500 turns on this winding!
O.K. so that covers the Power Transformer function.....in order to understand how the Output Transformer works, you have to understand that Ac voltages aren't always just 120v....tubes generate about what the plate voltage is (around 480v) AC output max which is way more than any speaker can handle, so another transformer steps this votage down to a managable level the speaker can use it.
Another thing about transformers is what they don't do, they don't pass DC (direct current) only AC since there is no physical connection between the windings. The primary side of the Output transformer has the full 480v running through it and the tubes modulate that voltage..(we'll leave it at that for now)
Because the amount of windings vary greatly to fit the application, other issues such as wire gauge come into play, and generally speaking the larger the transformer, the better quality....or the better power capability (has nothing to do with how the amp is voiced, just usually means it can handle more!) The size of the field created, the wire gauge and number of windings all determine how transformers pass electricity and bigger is not always better, just different.......
...well, this went way long, but hope it helped
Jeff Seal
Last edited:
Gearjoneser
Gear Ho
Re: So, in a tube amp, what's a transformer do?
Good info. All the details that go into making a great sounding transformer is similar to what makes certain pickups different from others. My question is, what variables in the construction of a transformer effect what frequencies? Normally, I like to see an amp that's got a giant iron tranny, not that space-saving coiled up type you see in power amps. What is bigger usually better, regarding transformers? More voltage?
Good info. All the details that go into making a great sounding transformer is similar to what makes certain pickups different from others. My question is, what variables in the construction of a transformer effect what frequencies? Normally, I like to see an amp that's got a giant iron tranny, not that space-saving coiled up type you see in power amps. What is bigger usually better, regarding transformers? More voltage?
Jeff Seal
New member
Re: So, in a tube amp, what's a transformer do?
Burned OT's are usually a result of running the amp without a load or into a dead shorted load. The coils heat up and the coating on the wire going around the core melts and finally makes contact with the core or other windings or both!....(or burns open)
However, if the amp is constantly pushing the OT to it's limitations, it's life will be greatly shorter than if the OT was capable of handling twice as much...(or more!). The transformer generates heat by itself while transferring power (referred to as "Eddy Currents") and the use of smaller transformer's pushed harder is causing a greater failure rate in OT's these days..
Since Transformers are the single most expensive component in any amp, it's not too difficult to understand why smaller, less expensive ones are becoming more predominant....This is the reason JCM900's weigh less than 800's or Plexi's...while Mesa Mark's weigh more than the Rectifier series.
Tonal issues are a little more complicated......and something I have a really good understanding of, but not enough to embarrass myself at a forum associated with Seymour Duncan himself......now there's a man who knows tone!
Jeff Seal
Burned OT's are usually a result of running the amp without a load or into a dead shorted load. The coils heat up and the coating on the wire going around the core melts and finally makes contact with the core or other windings or both!....(or burns open)
However, if the amp is constantly pushing the OT to it's limitations, it's life will be greatly shorter than if the OT was capable of handling twice as much...(or more!). The transformer generates heat by itself while transferring power (referred to as "Eddy Currents") and the use of smaller transformer's pushed harder is causing a greater failure rate in OT's these days..
Since Transformers are the single most expensive component in any amp, it's not too difficult to understand why smaller, less expensive ones are becoming more predominant....This is the reason JCM900's weigh less than 800's or Plexi's...while Mesa Mark's weigh more than the Rectifier series.
Tonal issues are a little more complicated......and something I have a really good understanding of, but not enough to embarrass myself at a forum associated with Seymour Duncan himself......now there's a man who knows tone!
Jeff Seal
Gearjoneser
Gear Ho
Re: So, in a tube amp, what's a transformer do?
Drake transformers are the "classic" tranny for Marshalls, and most people know they sound the best. I noticed that Marshall started using Axiom transformers, with plugs, not hardwired. I'm sure this has made servicing and building Marshalls a lot easier, but do those new Axioms hold a candle to a Drake? The only 'accepted' replacement tranny for Marshalls, these days, is Mercury Magnetics.
Drake transformers are the "classic" tranny for Marshalls, and most people know they sound the best. I noticed that Marshall started using Axiom transformers, with plugs, not hardwired. I'm sure this has made servicing and building Marshalls a lot easier, but do those new Axioms hold a candle to a Drake? The only 'accepted' replacement tranny for Marshalls, these days, is Mercury Magnetics.
JammerMatt
New member
Re: So, in a tube amp, what's a transformer do?
So, what's a rectifier do? What do two and three rectifiers do? Why not four? Or is it a sales gimmick?
-Matt
So, what's a rectifier do? What do two and three rectifiers do? Why not four? Or is it a sales gimmick?
-Matt
Re: So, in a tube amp, what's a transformer do?
I have a shorter explanantion for the output tranny, it converts the impedance of the speaker(s) to something that it's source impedance can drive effectively ... although I do like Jeff's version a bit better, without that tranny the output tubes couldn't drive the speakers ... not sure what exactly woould happen if you tried to hook them directly,asumming of course you decoupled the DC component. Oh rects, a rectifer is in the power supply input, it converts AC to DC needed in the amp to for both biases and the tube plates ... simply put soild state rects seem to be very fats and stable on there transients, while tubes rects can't resond as quick under transient demand ... so the actual power to the plates, and bias tends to *sag* a bit under drive ... this effects harmonics, and envelope dynamics of the amp ... not sure technically the reason for running two or more rects although than to get the effect exaggerated and more noticeable.Amps originall changed to SS rects because the tube dects were thought to be a bit undependandle ... strange when you consider that there are old Fenders, and Marshalls around that have their original tube rects, and have never been replaced, and work just fine. There are one or two SS rects that are made into a tube pin out modules, and are made as a direct replacement for a few of the tube rect (hence being made into a tube pin out m9dule) ... so you can experimant with using them if your amp has a tube rect. Also, SS rects are cheaper, and use a bit less components. Generally an amp with a SS rect will be tighter, and punchier sounding dynamically when cranked, and have a bit tighter sound overall, and a more accurate reproduction on the attack portion of the signal. Personal taste.JammerMatt said:
rhmcfarland
New member
Re: So, in a tube amp, what's a transformer do?
Hi Jeff. That's some excellent info. The rays of enlightenment making it even into my shadowy mind!
Tell me this: What's so special about Mercury Magnetics transformers? Same question with DeYoung Manufacturing. DMI is used in the SLO-100, and none of the other Soldano amps use them. None of the other Soldanos sound like the SLO, even though there are lots of other common components.
Hi Jeff. That's some excellent info. The rays of enlightenment making it even into my shadowy mind!
Tell me this: What's so special about Mercury Magnetics transformers? Same question with DeYoung Manufacturing. DMI is used in the SLO-100, and none of the other Soldano amps use them. None of the other Soldanos sound like the SLO, even though there are lots of other common components.
